The military uses ten miles in front of a storm (existing lightning
, rain) as a standard of safety
for closing down air fields and training. That's when the lightning is so far away that there is 50 seconds between the bolt and the boom. Lightning has been known to precede a storm by 10 miles. As for getting shocked without being part of the bolt, it has happened to me, too - shocked through the hands while holding a grounded helm
, with the bolt hitting the water
perhaps a mile away. My impression is 1. The electromagnetic field is a lot bigger than the bolt, and 2. Mr. Franklin was quite fortunate not to have become a crispy critter.